The invention relates to control of the regenerative braking in a vehicle equipped with a first, regenerative, braking means and with a second braking means separate from the first braking means, for example a hydraulic braking means.
The vehicle may, for example, be an electrical or hybrid vehicle.
On a vehicle equipped with at least one electrical traction or propulsion motor, it is possible under certain conditions to use the electric motor as a generator and thus to obtain an electrical braking means. Such a use is advantageous because, being regenerative, it makes it possible to recover some of the kinetic energy of the vehicle in order to recharge the batteries.
In the case of decoupled braking, the vehicle may for example comprise a distribution module (“Torque Blending”) arranged in order to distribute an overall braking command, coming from the brake pedal, between an electrical actuator and a hydraulic actuator. The situation is referred to as one with complementary braking setpoints.
According to another example, and particularly in the case of a vehicle with non-decoupled braking, a vehicle may comprise a braking management module (“Torque Manager”) arranged in order to generate an electrical braking setpoint as a function of the driver setpoint, for example proportional to this driver setpoint. The electrical braking setpoint is then a supplementary braking setpoint, which is added to the conventional hydraulic braking obtained directly from the brake pedal.
The regenerative braking setpoint, whether it is complementary or supplementary, is formed as a function not only of the driver setpoint coming from a brake pedal, but also as a function of other parameters, one of which is a signal indicating the stability of the vehicle.
Specifically, the electrical braking is only applied to the driving wheels, that is to say to the front wheel or wheels in the case of a front-wheel drive vehicle, or to the rear wheel or wheels in the case of a rear-wheel drive vehicle. The potential for regenerative braking is therefore more limited than braking applied to all the wheels.
This regenerative braking therefore risks causing greater slipping of the wheels in question, or even of causing locking of the wheels when the grip conditions are relatively precarious, for example in the case of a road which is wet or covered with ice or snow.
It is known to deactivate the regenerative braking when an active safety system, for example a system to prevent wheel lock, for example ABS (from the German “Antiblockiersystem”), and/or a system to prevent wheel slip, for example an ESC system (“Electronic Stability Control”), detects a hazardous situation, for example when a flag signal formed by this active safety system changes to 1.
These active safety systems are in communication with one or more sensors capable of providing information about the state of the wheels.
When the flag signal returns to zero, that is to say when the signals coming from the active safety systems correspond to a situation of sufficiently low risk, the regenerative braking is re-enabled.
Thus, Application FR2972411 discloses a flag signal referred to as “stability indicator”. However, its design and development complexity (in particular the calculation of the indicator on the basis of setpoints for correction of oversteer, for correction of understeer and for deceleration) make it relatively expensive.
There is a need for regenerative braking control which offers greater safety at lower cost.